The ultimate goal of this proposal is to identify sites of HIV-1 (HIV) persistence in the CNS, evaluate the characteristics and dynamics of HIV in these sites and test a novel preclinical approach for eradicating these sites. Rationale: The major target cells for HIV infection and persistence are T-cells and macrophages. With cART therapy, the number of HIV infected T-cells in the blood has dropped to virtually undetectable levels; however, sites of persistent tissue-based HIV infection and the evolution of that infection in virally suppressed individuals have not been well defined. Discontinuation of cART leads to recurrence of HIV viremia with viral strains not represented by those defined in the rare blood T-cell reservoir, suggesting the existence of a heretofore undefined tissue-based HIV reservoir. HIV infected macrophages have been implicated as a major viral tissue based reservoir in patients with HIV associated dementia (HAD) and unique brain-specific forms of HIV have been found at high levels in HAD patient brains. In patients with cART-mediated complete regulation of peripheral blood detectable HIV brain disease has changed significantly and the milder cognitive dysfunction syndromes associated with HIV infection have now been defined as HIV-associated neurocognitive disorders (HAND). The role that HIV might play in HAND has not yet been determined. With the emergence of atherosclerosis as a significant comorbidity in HIV-infected patients, it appears that a variation of vascular dementia may be becoming more frequent, implicating a potentially new type of HIV-associated CNS pathogenesis. The goal of this program is to define the sites and subspecies of HIV present in CNS and peripheral tissues in patients with well documented histories of cART associated viral suppression. Given the likelihood that a significant reservoir of HIV will be found in macrophages, a novel therapeutic that inhibits infection of macrophages and regulates monocyte differentiation so as to block ongoing migration into diseased tissues will be tested in a variety of in-vitro systems including functional brain cell cultures. Specific AIM 1: To identify and characterize the systemic cellular and genetic basis for HIV-1 persistence in the CNS and other reservoirs in autopsy tissues from a virally suppressed cohort. Specific AIM 2: Evaluate macrophage-localized HIV-1 reservoir virus variants for growth and functional effects in human macrophage and brain neuron/astrocyte cultures, and test functional effects of PA300, a novel regulator of HIV infection inhibitor and macrophage differentiation in such assays. Studies proposed will allow a definitive description of the HIV reservoir in patients treated with cART and provide in vitro support for a novel therapeutic approach that addresses the macrophage specific component of this reservoir.